If they continue with the thinly veiled plot lifts of OT movie, Rey will be semi-trained and then have to leave suddenly, facing Snoke/Kylo/someone and suffer a character-building defeat.
Though there have been a few pretty substantial hints as to how this will be a different movie.
- Daisy Ridley has commented on how the audience will love/be impressed with Luke in this movie, which to me hints to a more active role than Yoda had in Ep V. I, for one, really want to see that ol' green lightsaber in action again.
- It will start immediately after TFA, with the first conversation Rey and Luke have upon meeting on the Island of Wherever. That hints towards a focus on their relationship, and allows Luke to tell his side of the story on screen. Which in turn allows him to do a "what I tell you is the truth (from a certain point of view)" elaboration of who Snoke is, what happened to Ben Solo, and why he himself is hiding. Such a circumvention of the truth will create some drama when Rey finally finds out she's Snoke's brother's wookie's friend's daughter. Oy vey.